@article{JRAM_1879__88_148431,
     author = {A. Cayley},
     title = {On the addition of the double ...-functions.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {74--81},
     publisher = {mathdoc},
     volume = {88},
     year = {1879},
     zbl = {11.0322.03},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1879__88_148431/}
}